Immunomodulatory effects of a polysaccharide purified fromLepidium meyenii Walp. on macrophages
Wei Wang, Ye Zou, Qian Li, Riwen Mao, Xingjun Shao, Dun Jin, Daheng Zheng, Ting Zhao, Huifen Zhu, Lin Zhang, Liuqing Yang, Xiangyang Wu
A polysaccharide (MP21) was extracted and purified from Lepidium meyenii Walp. using DEAE-52 and Sephacryl™ S-500 columns. Its physicochemical properties and macrophage immunomodulatory activity were investigated in vitro. The results indicated that MP21 had an average molecular weight of 3.68 × 105 Da and was mainly composed of rhamnose, arabinose and galactose in a molar ratio of 1:4.84:5.34. The conformation of MP21 was between a sphere and random coil, and different treatments could change its conformation and asymmetry. RAW264.7 murine macrophages treated with MP21 could significantly inhibit the proliferation of human hepatocellular carcinoma HepG-2. MP21 could enhance the phagocytic capacity and induce elevated NO, ROS, TNF-α, and IL-1β secretion in RAW264.7 in a dose-dependent manner. MP21 promoted the expression of both iNOS protein and mRNA. The expression of the NF-κB p65 protein was also up-regulated by MP21. These results suggest that MP21 could exert cytotoxicity towards HepG-2 by activating macrophages via the NF-κB signaling pathway.
Circular dichroism, Biochemistry